U.S. patent application number 09/783859 was filed with the patent office on 2001-10-18 for monostable ferroelectric liquid crystal display apparatus.
Invention is credited to Isozaki, Tadaaki, Jisaki, Makoto, Nishimura, Teiichiro, Okabe, Eiji, Saito, Hideo, Shundo, Ryushi.
Application Number | 20010030731 09/783859 |
Document ID | / |
Family ID | 18567784 |
Filed Date | 2001-10-18 |
United States Patent
Application |
20010030731 |
Kind Code |
A1 |
Nishimura, Teiichiro ; et
al. |
October 18, 2001 |
Monostable ferroelectric liquid crystal display apparatus
Abstract
The present invention provides a monostable ferroelectric liquid
crystal display apparatus includes a pair of substrates, each
subjected to uniaxial orientation processing and arranged so that
their orientation processing directions are approximately parallel
to each other; and a ferroelectric liquid crystal material having
the chiral smectic C phase filled between the substrates, the
liquid crystal material being such that the projection component of
the cone drawn by a liquid crystal molecule of the ferroelectric
liquid crystal material projected onto the substrate and the
projection component of the liquid crystal molecule itself
projected onto the substrate in the molecule axis direction are
respectively identical to the orientation processing direction of
the substrates, which state is the initial state of the monostable
configuration, wherein the ferroelectric liquid crystal contains a
compound having a phenyl pyrimidine skeleton having one end
connected to an alkoxyl chain and the other end connected to an
alkyl chain, wherein sum of carbons in the alkoxyl chain and the
alkyl chain is 15. This enables to realize a monostable mode with a
sufficient stability even at low temperature and a sufficient
analog tone and contrast ratio.
Inventors: |
Nishimura, Teiichiro;
(Kanagawa, JP) ; Jisaki, Makoto; (Kanagawa,
JP) ; Isozaki, Tadaaki; (Kanagawa, JP) ;
Okabe, Eiji; (Chiba, JP) ; Shundo, Ryushi;
(Chiba, JP) ; Saito, Hideo; (Chiba, JP) |
Correspondence
Address: |
SONNENSCHEIN NATH & ROSENTHAL
P.O. BOX 061080
WACKER DRIVE STATION
CHICAGO
IL
60606-1080
US
|
Family ID: |
18567784 |
Appl. No.: |
09/783859 |
Filed: |
February 15, 2001 |
Current U.S.
Class: |
349/172 ;
252/299.61; 428/1.1 |
Current CPC
Class: |
Y10T 428/1036 20150115;
Y10T 428/10 20150115; G02F 1/141 20130101; C09K 19/42 20130101;
C09K 19/3458 20130101; C09K 2323/03 20200801; C09K 19/0225
20130101; C09K 2323/00 20200801 |
Class at
Publication: |
349/172 ;
252/299.61; 428/1.1 |
International
Class: |
C09K 019/02; C09K
019/34 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 17, 2000 |
JP |
P2000-045150 |
Claims
What is claimed is:
1. A monostable ferroelectric liquid crystal display apparatus
comprising: a pair of substrates, each subjected to uniaxial
orientation processing and arranged so that their orientation
processing directions are approximately parallel to each other, and
a ferroelectric liquid crystal material having the chiral smectic C
phase filled between the substrates, the liquid crystal material
being such that the projection component of the cone drawn by a
liquid crystal molecule of the ferroelectric liquid crystal
material projected onto the substrate and the projection component
of the liquid crystal molecule itself projected onto the substrate
in the molecule axis direction are respectively identical to the
orientation processing direction of the substrates, which state is
the initial state of the monostable configuration, wherein the
ferroelectric liquid crystal contains a compound having a phenyl
pyrimidine skeleton having one end connected to an alkoxyl chain
and the other end connected to an alkyl chain, wherein sum of
carbons in the alkoxyl chain and the alkyl chain is 15.
2. The monostable ferroelectric liquid crystal display apparatus as
claimed in claim 1, wherein the compound is at least one selected
from compounds shown in Chemical Formula 1 below wherein m=8 and
n=7, or m=7 and n=8. 7
3. The monostable ferroelectric liquid crystal display apparatus as
claimed in claim 1, wherein the liquid crystal material contains a
chiral component having spontaneous polarization, dicyclic phenyl
pyrimidine, and tricyclic phenyl pyrimidine.
4. The monostable ferroelectric liquid crystal display apparatus as
claimed in claim 1, wherein the content of the compound in the
liquid crystal material is in a range from 1 weight % to 60 weight
%.
Description
DETAILED DESCRIPTION OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a novel monostable
ferroelectric liquid crystal display apparatus using a liquid
crystal material having a chiral smectic C phase.
[0003] 2. Description of the Prior Art
[0004] Liquid crystal display elements have been widely used as
light-weight thin type display elements. Among them, twisted
nematic (TN) display elements of the TFT drive are especially
widely used.
[0005] However, the aforementioned display element has various
problems such as a tone reversal behavior in the middle tone, a
narrow viewing angle, a slow response time such as several
milliseconds or above, and the like. Especially the response time
between the middle tones reaches as much as 100 milliseconds or
above and the image display delay causes a tailing phenomenon.
[0006] In such a situation, a great expectation is posed on the
ferroelectric liquid crystal as a liquid crystal material which
improves the viewing angle and reduces the response time and its
application for display is considered.
[0007] For example, Clark et al suggests a surface-stabilized
ferroelectric liquid crystal display (SSFLCD) of the passive matrix
drive method utilizing a bistable memory in which the helical pitch
of the ferroelectric liquid crystal is untied in the narrow gap
cell to realize bistability having two memory states (see Appl.
Phys. Lett. 36, 899 (1980) and U.S. Pat. No. 4,367,924, Japanese
Patent Publication 60-22287).
[0008] This SSFLCD has an advantage that it is possible to realize
a white-black binary display element of a wide viewing angle.
[0009] However, for the image display speed increase, because of
the passive matrix drive method, the response time for one pixel is
as short as several microseconds but in the case of display having
plenty of pixels, the speed is not always increased. Accordingly,
the SSFLCD cannot be applied to the animation display in the
multimedia era.
[0010] Furthermore, the number of pixels is gradually increased,
starting in the so-called VGA, SVGA, XGA, SXGA, and UXGA. For the
large-capacity display, a principle of high-speed display is
expected.
[0011] To realize display of this high-speed response and wide
viewing angle, the applicant of the present invention has suggested
a monostable FLC mode in Japanese Patent Publication 4-212126 and
U.S. Pat. No. 5,214,523.
[0012] This mode utilizes a liquid crystal element having a pair of
substrates subjected to uniaxial orientation processing and
arranged in such a manner that the orientation processing
directions are almost in parallel to each other and a liquid
crystal material having the chiral smectic C phase filled between
the substrates. The component projected to the substrate in the
axis direction of the cone drawn by the liquid crystal molecule of
the liquid crystal material having the chiral smectic C phase and
the component projected to the substrate in the molecule axis
direction of the liquid crystal molecule itself are matched with
the substrate orientation processing directions, respectively,
which state is the initial state of the monostable configuration. A
switching element is arranged for each of the pixels, i.e., the
minimum unit for performing the active matrix drive. Voltage is
applied to continuously change the liquid crystal director
(molecule axis inclination) so as to perform analog modulation of
the transmitting light intensity, thereby realizing an analog tone
display of high speed and wide viewing angle as well as full-color
display.
[0013] More specifically, a transparent electrode side of a glass
plate on which a transparent electrode (ITO) is arranged is
subjected to the silane coupling processing. After this, the spin
coat method is used to apply a polyamide acid film, which is baked
to form a polyimide film. This polyimide film is subjected to
rubbing with a velvet cloth in one direction to obtain an
orientated film. The orientated film has a thickness of about 200
Angstrom and is asymmetric with respect to the rubbing direction to
obtain the liquid crystal orientation effect. Two of the glass
plate each having the orientated film thus prepared are arranged in
such a manner that the transparent electrodes oppose to each other
and the rubbing directions are anti-parallel to each other, thereby
assembling a cell with a 2-micrometer gap using an ultraviolet ray
setting adhesive in which 2-micrometer micropal is dispersed. The
liquid crystal material includes as the chiral component a compound
(a) shown in Chemical Formula 2 below and as the non-chiral
component, a tricyclic difluorine-based compound (b), phenyl
pyrimidine-based compound (c), and phenyl benzoate-based compound
(d), thereby realizing a monostable FLC mode. 1
[0014] However, with the aforementioned liquid crystal composite
material, it is impossible to obtain a sufficient black level
sinking to obtain a sufficient contrast ratio. Moreover, the
monostability of the aforementioned liquid crystal composite
material when subjected to an electric field is insufficient.
[0015] Japanese Patent Publication 11-125182 discloses that the
aforementioned liquid crystal composite material can increase the
contrast ration when containing phenyl pyrimidine connected an
alkyl chain having 17 carbons at the both ends. Moreover, Japanese
Patent Publication 11-151755 discloses that the aforementioned
liquid crystal composite material can increase its monostability
when containing biphenyl pyrimidine connected to an alkyl chain
having an even number of carbons at the both ends.
[0016] However, when the liquid crystal composition contains phenyl
pyrimidine connected to an alkyl chain having 17 carbons at the
both ends or biphenyl pyrimidine connected to an alkyl chain having
an even number of carbons at the both ends, the melting point is
increased and the liquid crystal material is crystalized at room
temperature. For this, it is impossible to use a monostable
ferroelectric liquid crystal apparatus prepared using this liquid
crystal material at room temperature.
SUMMARY OF THE INVENTION
[0017] It is therefore an object of the present invention to
provide a monostable ferroelectric liquid crystal display apparatus
capable realizing a monostable mode with a sufficient stability
even at room temperature and a sufficient analog tone and contrast
ratio.
[0018] The inventors of the present invention, during development
of a monostable ferroelectric liquid crystal display apparatus,
found that a liquid crystal material containing dicyclic phenyl
pyrimidine has a lowered melting point when the phenyl pyrimidine
skeleton has one end connected to an alkoxyl chain and the other
end connected to an alkyl chain wherein the sum of carbons in the
alkoxyl chain and the alkyl chain is 15. This realizes a monostable
mode specifically stable at the room temperature and improves the
analog tone and the contrast ratio.
[0019] The monostable ferroelectric liquid crystal display
apparatus according to the present invention includes: a pair of
substrates, each subjected to uniaxial orientation processing and
arranged so that their orientation processing directions are
approximately parallel to each other; and a ferroelectric liquid
crystal material having the chiral smectic C phase filled between
the substrates, the liquid crystal material being such that the
projection component of the cone drawn by a liquid crystal molecule
of the ferroelectric liquid crystal material projected onto the
substrate and the projection component of the liquid crystal
molecule itself projected onto the substrate in the molecule axis
direction are respectively identical to the orientation processing
direction of the substrates, which state is the initial state of
the monostable configuration, wherein the ferroelectric liquid
crystal contains a compound having a phenyl pyrimidine skeleton
having one end connected to an alkoxyl chain and the other end
connected to an alkyl chain, wherein sum of carbons in the alkoxyl
chain and the alkyl chain is 15.
[0020] By adding dicyclic phenyl pyrimidine having a phenyl
pyrimidine skeleton having one end connected to an alkoxyl chain
and the other end connected to an alkyl chain wherein the sum of
carbons in the alkoxyl chain and the alkyl chain is 15, it is
possible to realize a stable monostable FLC mode and significantly
improve the analog tone, black level, and contrast ratio as well as
lower the melting point although no detailed reason is known.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] FIG. 1 is a perspective view schematically showing a
configuration example of a liquid crystal cell in a monostable
ferroelectric liquid crystal display apparatus.
[0022] FIG. 2 schematically shows a cone drawn by a liquid crystal
molecule.
[0023] FIG. 3 schematically shows a behavior of liquid crystal
molecules viewed from the direction indicated by the arrow "a" in
FIG. 1.
[0024] FIG. 4 schematically shows a behavior of the liquid crystal
molecules viewed from the direction indicated by the arrow "b" in
FIG. 1.
[0025] FIG. 5 schematically shows a behavior of the liquid crystal
molecules viewed from the direction indicated by the arrow "c" in
FIG. 1.
[0026] FIG. 6 is a flowchart showing a procedure for manufacturing
a display panel.
[0027] FIG. 7 graphically shows the relationship of the content of
alkoxyl phenyl pyrimidine having 7 carbons in the alkoxyl chain and
8 carbons in the alkyl chain with the melting point of the liquid
crystal composite material.
[0028] FIG. 8 graphically shows the relationship of the content of
alkoxyl phenyl pyrimidine having 8 carbons in the alkoxyl chain and
7 carbons in the alkyl chain with the melting point of the liquid
crystal composite material.
[0029] FIG. 9 graphically shows the relationship of the content of
a 1:1 mixture of alkoxyl phenyl pyrimidine having 7 carbons in the
alkoxyl chain and 8 carbons in the alkyl chain and alkoxyl phenyl
pyrimidine having 8 carbons in the alkoxyl chain and 7 carbons in
the alkyl chain with the melting point of the liquid crystal
composite material.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0030] Description will now be directed to a monostable
ferroelectric liquid crystal display apparatus according to the
present invention with reference to the attached drawings.
[0031] The monostable ferroelectric liquid crystal display
apparatus according to the present invention has a basic
configuration as shown in FIG. 1 for example. That is, substrates 1
and 2 each has been subjected to the uniaxial orientation
processing such as the rubbing and the oblique deposition are
arranged with their surfaces opposing to each other, thereby
constituting a liquid crystal cell and a space between the
substrates 1 and 2 is filled with a liquid crystal material having
the chiral smectic C phase (hereinafter, referred to as SmC*
phase).
[0032] Each of the substrates 1 and 2 includes a transparent
electrode formed on a transparent substrate and the transparent
electrode is covered with a polyimide film, which is subjected to
the rubbing or with an oblique deposition film. The substrates 1
and 2 are positioned so that their uniaxial orientation processing
directions (indicated by X and Y in FIG. 1) are approximately in
parallel to each other.
[0033] Here, the rubbing process is a technique to rub the surface
of the polyimide film in one direction to cause fine scratches on
its surface so as to obtain an orientation. The arrangement may be
such that the rubbing directions are identical (completely
parallel, hereinafter, referred to as parallel) or the rubbing
directions are opposite to each other (hereinafter, referred to as
anti-parallel). That is, the former is a case when the rubbing
direction of the substrate 1 is X.sub.1 while the rubbing direction
of the substrate 2 is Y.sub.1; and the latter is a case when the
rubbing direction of the substrate 1 is X.sub.1 while the rubbing
direction of the substrate 2 is Y.sub.2.
[0034] As has been described above, the upper and the lower
substrates 1 and 2 are subjected to the uniaxial orientation
processing and they are arranged with their orientation directions
in approximately parallel to each other to constitute a liquid
crystal cell, which is filled with a liquid crystal material having
the SmC* phase. For example, when the liquid crystal material has a
layered structure, the normal direction of each of the layer (or
its projection component direction to the substrate) is matched
with the aforementioned orientation process direction.
[0035] Here, as shown in FIG. 2, a liquid crystal molecule 3 of
each layer is rotated along the circumferential surface of a cone.
The direction Z of the axis of the cone drawn by this liquid
crystal molecule (or direction of its projection component to the
substrate) is also matched with the aforementioned orientation
process direction. Furthermore, the direction D of the director
(molecule axis) of the liquid crystal molecule 3 itself (or the
direction of its projection component to the substrate) is also
matched with the aforementioned orientation process direction. That
is, each of the liquid crystal molecules 3 is stabilized at the
position of point r or point s on the cone circumference. This
state is defined as memory cone 0 degree.
[0036] Accordingly, the ferroelectric liquid crystal display
apparatus according to the present invention utilizes the
stabilization effect of the liquid crystal molecule on the
substrate surface. However, it is not the known bistability (memory
cone 30 degrees to 45 degrees) or a one-side stability of
stabilization in bistability, but monostabilized in a state between
them (memory cone 2 degrees or less).
[0037] The aforementioned ferroelectric liquid crystal display
apparatus, when viewed from the normal direction of the substrates
1 and 2, has a configuration that the uniaxial orientation
directions X and Y of the substrates 1 and 2 in a state not
subjected to an electric field, the axis direction Z of the cone
drawn by the liquid crystal molecule 3, and the direction D of the
director of the liquid crystal molecule 3 itself are matched with
one another.
[0038] Here, while maintaining the polarization direction A of an
analyzer orthogonal to the polarization direction P of a polarizer,
if one of the polarization directions is matched with the
aforementioned orientation process direction, no light penetrates
and a black level is obtained.
[0039] In contrast to this, when an electric field is applied, the
director of the liquid crystal molecule 3 is rotated along the cone
and tilted continuously (in analog way) to the right or left
according to the electric field intensity and the polarity,
enabling to obtain a continuous tone (analog tone).
[0040] It should be noted that the electric field applied may have
any drive voltage waveform but it is preferable to be an amplitude
modulation type with an alternation between plus (+) and minus (-)
almost satisfying the electrically neutral condition.
[0041] The behavior of the liquid crystal molecule is shown in FIG.
3 to FIG. 5. FIG. 3 shows the behavior of the liquid crystal
molecule viewed from the direction "a" in FIG. 1. FIG. 4 shows the
behavior of the liquid crystal molecule viewed from the direction
"b" in FIG. 1. FIG. 5 shows the behavior of the liquid crystal
molecule viewed from the direction "c" in FIG. 1. Moreover, in
these figures, the substrates 1 and 2 are arranged as glass
substrates 1a and 2a having transparent electrodes 1b and 2b and
rubbing processed layers 1c and 2c.
[0042] When no electric field is applied, the direction D of the
directors of the respective liquid crystal molecules 3 are matched
with the uniaxial orientation process direction of the rubbing
processed layers 1c and 2c of the substrates 1 and 2. That is, as
shown in the center of FIG. 3 to FIG. 5, the direction D of the
directors of the liquid crystal molecules 3 are at the center of
the projection plane of the cone.
[0043] This state is the monostable state. For example, when the
polarization direction P of the polarizer is mated with the
orientation process directions X and Y and the polarization
direction A of the analyzer is orthogonal to this, no light
penetrate, making a dark state.
[0044] On the other hand, for example, when plus (+) is applied to
the transparent electrode 1b of the upper substrate 1 and minus (-)
is applied to the transparent electrode 2b of the lower substrate
2, as shown at left of the respective figures, the liquid crystal
molecule 3 is rotated in the counterclockwise direction (the
rotation direction depends on the polarity of the spontaneous
polarization of the liquid crystal material). Here, the apparent
tilt angle .theta. is increased as the distance from the boundary
with the rubbing processed layers 1c and 2c is increased. The
reason is considered to be that the interaction is intense at the
boundary with the rubbing processed layers 1c and 2c, causing a
so-called anchor effect.
[0045] Here, the maximum value .theta..sub.MAX of the apparent tilt
angle .theta. is determined by the electric field intensity.
Accordingly, the tilt angle maximum value .theta..sub.MAX is
continuously changed according to the electric field intensity. Of
course, this is accompanied by a continuous change of an average
value .theta..sub.AVG of the apparent tilt angle viewed as the
entire liquid crystal cell.
[0046] Similarly, when a minus (-) electric field is applied to the
transparent electrode 1b of the upper substrate 1 and a plus (+)
electric field is applied to the transparent electrode 2b of the
lower substrate 2, as shown at the right in the figures, the liquid
crystal molecule 3 is rotated clockwise and the maximum value
.theta..sub.MAX and the average value .theta..sub.AVG of the
apparent tilt angle are continuously changed.
[0047] Here, the linear polarization from the polarizer causes a
phase difference due to the tilt of the director of this liquid
crystal molecule 3, thereby becoming an elliptical polarization.
Accordingly, the penetrating light amount from the analyzer becomes
greater according to the tilt angle average value .theta..sub.AVG.
That is, the penetrating light intensity I in the liquid crystal
cell can be expressed by Expression 1 below and is changed
according to the apparent tilt angle average value .theta..sub.AVG,
thereby enabling to obtain an analog tone.
I.varies.I.sub.0 sin.sup.22.theta. Expression 1
[0048] wherein I.sub.0 is the light intensity before penetrating
through the cell.
[0049] After the external electric field is removed from the
electric field applied state, the internal electric field in the
liquid crystal and the stabilization effect on the boundary work to
readily set the initial state.
[0050] In the aforementioned liquid crystal display apparatus, the
liquid crystal material used may be any liquid crystal material
which can have the SmC* phase. However, when considering the
orientation characteristic, it is preferable that the SmC* phase
have a sufficiently long helical pitch and further a great
spontaneous polarization and exhibit the SmC* phase in a wide
temperature range including the room temperature.
[0051] Accordingly, it is preferable to use a mixture of a
conventionally known chiral liquid crystal and a non-chiral liquid
crystal (host liquid crystal) such as tricyclic ester
fluorine-substituted derivative, phenyl pyrimidine-based material,
phenyl benzoate-based material, and the like.
[0052] Especially, in order to obtain a stable monostable
structure, the non-chiral liquid crystal is preferably a phenyl
pyrimidine-based liquid crystal, among which it is especially
preferable to use a mixture of dicyclic phenyl pyrimidine and
tricyclic phenyl pyrimidine. The phenyl pyrimidine-based liquid
crystal is most preferable from the viewpoint of defects.
[0053] Moreover, when using the mixture of a chiral liquid crystal
and a non-chiral liquid crystal, the amount of the chiral liquid
crystal added to the non-chiral liquid crystal as the host liquid
crystal affects the contrast and the response time. In order to
maintain a practical response time as well as to realize a high
contrast, the amount of the chiral liquid crystal added is
preferable in a range from 1 weight % to 20 weight %.
[0054] The present invention is characterized in that the
aforementioned liquid crystal material contains a compound having a
phenyl pyrimidine skeleton having one end connected to an alkoxyl
chain and the other end connected to an alkyl chain, and the sum of
the carbons in the alkoxyl chain and the alkyl chain is 15.
[0055] More specifically, the compound added is expressed by
Chemical Formula 3 and Chemical Formula 4 below in which m=8 and
n=7, or m=7 and n=8. 2
[0056] this lower the melting point of the liquid crystal material,
realizing a monostable mode which is peculiarly stable even at room
temperature. This improves the analog tone, the black level, and
the contrast ratio.
[0057] It should be noted that the content of the aforementioned
compound in the liquid crystal material is preferably in a range
from 1 weight % to 60 weight %. If the content of the compound is
below 1 weight %, the effect to lower the melting point of the
liquid crystal material cannot be expected. Moreover, the content
of the aforementioned compound is practically limited to 60 weight
% and if the content exceeds 60 weight %, the temperature range
capable of realizing the SmC* phase of the liquid crystal material
is decreased.
EXAMPLES
[0058] Hereinafter, examples of the present invention will be
explained through specific experiment results.
[0059] Preparation of the display panel
[0060] Firstly, explanation will be given on the method how the
display panel to be used in the examples was prepared.
[0061] Explanation will be given on a process preparing a panel
using a glass cell (see FIG. 6).
[0062] a) Panel cleaning (step a and step b)
[0063] ultrasonic washing using alkali, water shower 4 times
(ultrasonic), hot water washing (step a), UV ozone processing (step
b)
[0064] b) Polyimide film formation step (step c)
[0065] spin coating (1000 rpm/5 seconds, and 3500 rpm/30 seconds),
and then placed in a nitrogen box for 1 day
[0066] c) rubbing (step d)
[0067] As shown in FIG. 1, rubbing was performed so as to obtain an
assembly parallel to the rubbing direction and in an anti-parallel
state. The rubbing condition was set as follows: 300 rpm, table
speed 2 mm/second, pushing-in amount 0.2 mm.
[0068] d) assembling (step e)
[0069] A seal agent was applied onto the opposing substrates by the
screen printing method or using a dispenser and assembling was
performed in parallel.
[0070] e) injection (step f)
[0071] The liquid crystal material to be injected is adhered to a
top of an injection hole and injected by the capillarity using a
hot stage (trade name FP82 produced by Mettler Co., Ltd.) under a
temperature higher by 10 degrees C. to 20 degrees C. than the
nematic-isotropic phase transition temperature. After this, a
nitrogen gas was used to slowly return to the normal pressure and
then to the normal temperature.
Example 1
[0072] A material consisting of compounds a to e shown in Chemical
formula 5 below was used as a basic component of a liquid crystal
material A and the melting point was measured. To this liquid
crystal material A, alkoxyl phenyl pyrimidine shown in Chemical
Formula 6 below was added in various amounts and the melting point
and the memory cone were measured. 3
Example 2
[0073] Instead of the alkoxyl phenyl pyrimidine shown in Chemical
Formula 6, alkoxyl phenyl pyrimidine shown in Chemical Formula 7
below was added to the liquid crystal material A and the melting
point and the memory cone were measured in the same way as in
Example 1. 4
Example 3
[0074] Instead of adding only the alkoxyl phenyl pyrimidine shown
in Chemical Formula 6, the alkoxyl phenyl pyrimidines shown in
Chemical Formulae 6 and 7 below were added with a mixing ratio of
1:1 to the liquid crystal material A and the melting point was
measured in the same way as in Example 1.
Comparative Example 1
[0075] Instead of the alkoxyl phenyl pyrimidine shown in Chemical
Formula 6, alkoxyl phenyl pyrimidine shown in Chemical Formula 8
below was added to the liquid crystal material A and the melting
point and the memory cone were measured in the same way as in
Example 1. 5
Comparative Example 2
[0076] Instead of the alkoxyl phenyl pyrimidine shown in Chemical
Formula 6, alkoxyl phenyl pyrimidine shown in Chemical Formula 9
below was added to the liquid crystal material A and the melting
point and the memory cone were measured in the same way as in
Example 1. 6
[0077] Firstly, FIG. 7 shows the measuring result of the melting
point in Example 1; FIG. 8 shows the measurement result of the
melting point in Example 2; and FIG. 9 shows the measurement result
of the melting point in Example 3.
[0078] As shown in FIG. 7, when the alkoxyl phenyl pyrimidine shown
in Chemical Formula 6 was added, the melting point of the liquid
crystal material was already lowered when the concentration was 1%.
The melting point was lowered down to 11 degrees C. when the
concentration was 50%. Especially when the concentration was 40%,
the melting point of the liquid crystal material was lowered down
to 9 degrees C.
[0079] Moreover, as shown in FIG. 8, when the alkoxyl phenyl
pyrimidine shown in Chemical Formula 7 was added, the melting point
of the liquid crystal material was already lowered when the
concentration was 1%. The melting point was lowered down to 12
degrees C. when the concentration was 60%.
[0080] Moreover, as shown in FIG. 9, when the alkoxyl phenyl
pyrimidines shown in Chemical Formulae 6 and 7 were added with a
mixture ratio of 1:1, the melting point of the liquid crystal
material was already lowered when the concentration was 1%. The
melting point was lowered down to 2 degrees C. when the
concentration was 60%.
[0081] These results show that the melting point of the liquid
crystal material can be lowered by adding a compound having a
phenyl pyrimidine skeleton having one end connected to an alkoxyl
chain and the other end connected to an alkyl chain, and the sum of
carbons in the alkoxyl chain and the alkyl chain is 15.
[0082] Next, Table 1 shows the measurement results of the memory
cone in Example 1, Example 2, Comparative Example 1, and
Comparative Example 2.
1 TABLE 1 Memory cone (degree) Example 1 0.0 Example 2 0.0
Comparative 2.9 Example 1 Comparative 3.2 Example 2
[0083] As shown in Table 1, when the alkoxyl phenyl pyrimidines
shown in Chemical Formulae 6 and 7 were added, the memory cone was
0 degree. In other words, monostability was maintained. However,
when the alkoxyl phenyl pyrimidines shown in Chemical Formulae 8
and 9 were added, the memory cone was 2 degrees or more. In other
words, it was impossible to maintain monostability.
[0084] This shows that it is possible to maintain monostability by
adding a compound having a phenyl pyrimidine skeleton having one
end connected to an alkoxyl chain and the other end connected to an
alkyl chain, and the sum of the carbons in the alkoxyl chain and
the alkyl chain is 15.
[0085] As is clear from the aforementioned, according to the
present invention, it is possible to provide a liquid crystal
material having a low melting point and stable monostable mode by
adding a compound having a phenyl pyrimidine skeleton having one
end connected to an alkoxyl chain and the other end connected to an
alkyl chain, and the sum of the carbons in the alkoxyl chain and
the alkyl chain is 15. This enables to provide a monostable
ferroelectric liquid crystal display apparatus having a sufficient
analog tone, a high contrast ratio, and a high black level even at
the room temperature.
[0086] As is clear from the aforementioned, according to the
present invention, it is possible to provide a liquid crystal
material having a low melting point and stable monostable mode.
This enables to provide a monostable ferroelectric liquid crystal
apparatus having a sufficient analog tone, a high contrast ratio,
and a high black level even at the room temperature.
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